Retractable aircraft undercarriage



Patented Jan. 26,` 1954 2,657g316 ICE 2,667,316 RETRACTABLE AIRCRAFTUNDERCARRIAGE Robert C. Winter, Grand Island, Corporation,

Buffalo, and John W. Wheeler, N. Y., assignors to Bell AircraftWheateld, N. Y.

Application April 25, 1951, Serial No. 222,856

Claims.

'I'his invention relates to aircraft retractable undercarriage devices,and more particularly to improvements in landing wheel strut devices ofthe type that provide for swinging of the strut from landing positioninto a recessed body portion of the aircraft while at the same timerotating automatically about its long axis so as to turn the landingwheel to t substantially horizontally atwise into the aircraft bodyrecess.

Therefore it is an object of the present invention to provide inaircraft an improved retractable landing wheel strut of the type whereinincidental to fore and aft swinging of the strut in a flat plane betweenextended and retracted positions, the strut and landing wheel unitrotates automatically so as to dispose the wheel in fore and aftdirectional alignment when the gear is in extended position, and insubstantially horizontally flatwise stowed position within a wheel wellformed in the aircraft underbody when the gear is in retracted position.Other more specific objects and advantages of the invention will appearin the specification hereinafter.

In the drawings:

Fig. 1 is a fragmentary side elevational view of a landing gear unitembodying the present invention; the landing wheel and strut unit beingshown by full lines in its extended position, and by broken lines in itsretracted position;

Fig. 2 is a front elevational View of the landing gear unit of Fig. 1,shown in its extended or landing position;

Fig. 3 is a fragmentary top plan view, on a larger scale, of the unit ofFigs. 1-2; and

Fig. 4 is a fragmentary section taken along line IV-IV of Fig. 3.

. As shown in the drawing, be embodied in an airplane structureincluding a body portion I0 which is recessed to provide a wellformation as indicated at I2 for accommodation of an undercarriage strutcarrying a landing wheel I 4. 'I'he strut device includes a pair oftelescopic members I-I which are angularly locked together as by meansof a spline or key and keyway connection; and it will be understood thatsuitable shock absorbing means (not shown) may be installed within the.unit so as to provide the strut assembly with desired shock absorbingcharacteristics, as is well known in the art. The outer strut member I8is in turn rotatably mounted within a trunnion sleeve bracket 29; theupper end of which is equipped with diametrically extending pivot pindevices 2 I2I engaging corresponding trunnion bearings 22-22 which arecarried by brackets 23-23 forming parts of the braced structure of theyaircraft body. The aligned axes of the pins 2I-2I are disposedhorizontally and transversely of the fore -and aft axis of the aircraft,and thus the strut and wheel unit is thereby mounted upon the aircraftso as to swing in fore and aft directions therebelow. As shown in Fig.l, a hydraulic jack or the like as indicated, at 24 may be mounttheinvention may ed as by means of connections 2&-23 for actuating thewheel strut unit between extended and retracted positions thereof asshown by the solid line and broken line illustrations thereofrespectively in Fig. 1. However, it will of course be appreciated thatany other suitable means for swinging and bracing the Wheel strut unitabout the axis of the pins 2I-2I may be employed if preferred.

To control the rotational position of the strut-A wheel unit relative tothe trunnion bracket 2G so as to automatically dispose the landing wheelin a position of fore and aft alignment when the gear is in extendedposition and to turn the wheel so as to lie iiatwise within the well I2when the gear is retracted, we provide a novel rotating control deviceas follows. The strut element I8 is formed to include an extensionelement 30 (Fig.V 4) formed integrally therewith. At its upper end thestrut extension element 3! carries a cap Vdevice 3i whichis rmly fixedthereto as by means of a bolt 32 (Fig. 3). The cap 3l is formed with apair of ears 33-33 hanging downwardly outside of the upper end Of thetrunnion bracket 28, and carrying corresponding pi-vot connectiondevices 34-3/3. The pivot connection devices 34-34 are arranged indiametrically opposed relation about the upright axis of the strut unit,but the axes of the pivot devices 34-34 are aligned in a direction at 45to the direction of alignment of the trunnion bearing pins 2I-2I (Fig.3). The pivot connections 34-34 connect to the corresponding endportions of a yoke device 35 which includes a stub shaft portion 36extending from the head thereof. The shaft 36 fits in rotational bearingrelation with the bearing socket portion 38 of a bracket 40 (Fig. l)which is Xed to the stationary frame work of the aircraft body.

The bearing socket portion 38 and the bracket 4U and the yoke device 35are all so dimensioned and relatively arranged that the bracket bearingconnection supports and maintains the stub shaft portion 35 of the yoke35 to extend at a 45 angle from horizontal and at a 45 angle in planview from the fore and aft directional axis cf the aircraft. Thus,beginning for example from the position of extension of the gear, as thewheel strut is pulled rearwardly upon by the hydraulic jack 24 thecontrol cap and yoke devices 3I-35 cooperate to cause the strut wheelunit to rotate about the longitudinal axis thereof within the trunnionbracket sleeve 20 without interference with the free swinging movementthereof in a line straight fore and aft of the aircraft. This action ofthe cap and yoke devices 3I-35 controls the wheel-strut unit so that asthe strut approaches its horizontal broken line position thereof asshown in Fig. 1, the wheel has been rotated and thus moves into theaircraft underbody well portion I2 in a straight atwise attitude.Reversely, when the hydraulic jack is actuated to lower the gear thewheel-strut unit descends and same time the cap and yoke devices 3|-35oper. f f

ate automatically to cause the wheel to reverse rotate 90 and into itsfore and :raft direoti'onally `i5 aligned attitude as shown inthedrawing. ln event the Vwheel needs to be rotated throughan Y angle otherthan 90 as described hereinabove;thc' angles at which the stub shaft 36extends from the upper end of the wheel-strut-unit will becor- 10respondingly adjusted away from the 45 yangle arrangements as describedhereinabove.

A s stated hereinabove, it is aparticular feature of the presentinvention that the mechanism thereof .operates automatically to lproduce concurrent motion of the strut about two axes to provide thedesired control of `the wheel-strut unit whileat the Same 'time avoidingany binding of the relatively moving parts and neoessitvior swinging.through an are having aiateral com- 20 ponent. -It will also beappreciated 'that the mechanismof -the .present invention-accomplishesthe desired objects and `eiects 'through .useof .a

' greatly Simpliedstructuralmeehanism comprising a minimum number ofparts whicharereadily 25 and inexpensively fabricated to .be ,so Arugged,as

to easily withstand 'the rigors of service. lliurthermore, thestrutmounting arrangementof the invention provides for most vdirect andeiicient handling of the primaryiandng lloads through 0 the pivotsupports of the gear; and thus .the landing vrgear of theinvention notonly provides an improved mode of retraction-.operation but alsoiobtains.the advantages thereof in combination with 4Va structural organizationwhich .may o readily and inexpensively be ;tabricated to be of extremelysimple and light weghtyet rugged characteristics.

What isolaimed is: Y A

1. ,Anaircrait retractable landinggear including a .trunnion .bracketpivotally mounted upon the aircraft to swing tin straight `fore and aftdi rections thereon about a ,first vaxis, a wheelstrut rotatablyjournaled within said Atrunnion bracket and extending therebelow forground Contact purposes, .power .means tor swinging .said .bracketrelative to the aircraft in tore andaft. directions betweenpextended andretracted positions, and wheel strut rotation control means .comprising.a iirstyoke member keyed to said rotatable wheel strut; and a secondyoke member pivotally confA nested l.at .corresponding .opposite yokearm end portions 'to said nrst yokemernber alonga second axis .extendingoblouely to said 'first .axis ,Said .Second yoke member having a StubShaft `head 1 portion thereof rotatably .retained within a fixedbearingportion of theaircraft structure,

2. An aircraft retractable -landing gear comprisirigl a trunnion bracketpivotally Y Irlounted upon the .aircraft to swing in straight fore ,andaft directions thereon about a first axis, a wheel strut journaledwithinsaid trunnion bracket to be rotatable therein and extending'therebelow f or ground contact purposes, powermeans -for swinging saidbracket relative vto the aircraft jin foreand aft .directions 'betweenextended and retracted positions, and wheel strutrotation control meanscomprising a rstyoke lmemberkeyed to said rotatable wheel strut, and a'second yoke memberpivotally connected at corresponding `o o- 70 positeyoke arm ,end portions with said viirstj yoke member, said second yokemember `having `a stub shaft .head portion thereof rotatably 4retainedwithin a fixed bearing portion o f the aircraftstructure and rotatabletherein about a second :extending both herizontaiiyane -yerticauyobliquely relative to said iirst axis.

- (3. An aircraft retractable landing gear com-V prising a trunnonbracket pivotally mounted 4.upon .the .aircraft to .swing in straightfore and aftdileotions ,thol'eQILabout a rst axis, a wheel strutijournaled within said trunnion bracket for rotation ,and Y exto r1,`c'iin, therebelow for ground contact purposes, power means for swingingsaid '-,bra'oket relative VYto lthe aircraft in fore and aft directionsbetween extended and retracted positions, and wheel strut rotationcontrol means comprising a rst yoke member keyed to said rotatable wheelstrut, and a second yoke jmembor pivotalhr connected yat correspondingopposite yoke arm end Yportions Yto said rstgyokememf ber along a secondaxis extending obligueiyfrelative lto said rst axis, fsaid 'second yoke'member havinga stub shaft head portion `thereof rotatably retainedwithin a lfixed :bearing portion of the aircraft structure, and havingan axis vofretation therein obliguely intersecting said Yjid-st axls;

`4, aircraft retractable landing gear comprising -a 'trunnion bracketpivotall-y *mounted upon the aircraft to 4swing A"in straight fore anda'ft dir ectionsthereoma wheel strut journaled within saidtrunnionvibracket Lto be rotatable thereinand lextendingtherebelowfior-ground contact purposes, means for swinging said bracketrelative vto the yaircraft in'gfore and aft ldirections between extendedYand retracted -positions, `and wheel strut rotation `control meanscomprising a pair of yoke members -pivotallyconnected to eachother, oneo'fsaid yoke I nen'ib'ers being Ikeyed to said rotatable wheels'trut,fand 'the other o'f said yoke members having astub Isha-ft 1headportion thereof rotatably retainedwithi-n afixedbearing portion of theairora-tt structure and rotatable therein about -an axis skewed 1in two-direc-V tions relative' to ithe 'axis of pivoting cfsaid trunnionbracket.

A5. An :aircraft Aretractable flanding gear Icomprising a trunnionfbracket Vfp'ivotally Imounted upon the aircraft to swing in straightyfore and aft :.directions'thereon, a twheel strut gjournaled withinsaiditrunnionibracketand--rotatamethere- Y in kand Aextendingitherebelowfor ground contact purposes, means for swinging said 'bracketrelative to 'the aircraft in ffore and raft-directions Joetween.extended .and retracted positions, fand wheel :strut rotation 4controlmeansvr :comprising a rst yoke member keyed `Ito said rotatable wheelstrut, .and :la second `yoke l member pivotally connected with :said`firstfyoke member, said -second yoke :member having a stub shaft headportion .thereof :rotatably :retained .within a v-iixed bearing portionof 1:the :aircraft structure and Y'rotatable stherein about an .axisintersecting andV inclined approximately :45 degrees horizontallyandyertioa'lly away ffrom the axis of pivoting of Said-trunnionbracket.

